Chamalycaeus mizoramensis Páll-Gergely & Aravind, 2025

Chamalycaeus mizoramensis Páll-Gergely & Aravind sp. nov.

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Fig. 4

Diagnosis

A relatively large species of Chamalycaeus with a ca half whorl-long R2+R3, and R3 with a low central swelling and a fringed aperture.

Etymology

This species is named after the state of Mizoram, where the Blue Mountain is situated.

Type material examined

Holotype

INDIA – Mizoram • empty shell (D: 4.8 mm, H: 3 mm); Blue Mountain, Lawngtlai district ; 22.727° N, 93.135° E; 1400 m a.s.l.; 27 Jan. 2019; N.A. Aravind leg.; AR15; NZSI LM1715 View Materials . GoogleMaps

Description

Shell off-white/ivory in colour, not translucent; shell outline slightly oval in dorsal view; spire slightly elevated, low conical; body whorl rounded; protoconch low, finely granular, spiral striae lacking, consisting of nearly 2 whorls; R1 of 1.75 whorls, with rather irregular, dense, low ribs (last half whorl of R1 with ca 55–60 ribs) and weaker, denser spiral striation; boundary between R1 and R2 not conspicuous because R2 ribs are only slightly higher and sharper than R1 ribs, but R2 area more inflated than R1; sutural tube conspicuously shorter than R2, probably due to teratological condition; R2 with ca 50– 52 straight, sharp but low ribs; R2+R3 ca half whorl, R3 shorter than R2, boundary between R2 and R3 clearly visible due to a slight constriction; R3 with long and low central swelling; R3 ribs stand approximately as densely as R1 ribs, with the exception of the beginning of R3 with more widely-spaced ribbing; aperture strongly oblique to shell axis, rounded with 5 small bays on the palatal side, resulting in a fringed peristome; boundary between inner and outer peristomes is not conspicuous but clearly visible, inner peristome thickened, slightly protruding and expanded; outer peristome thin, sharp, slightly expanded, especially towards umbilicus; umbilicus relatively narrow, ca one fourth of shell width, rounded.

MEASUREMENTS. D: 4.8 mm, H: 3 mm.

Distribution

Known only from the Blue Mountain region.

Differential diagnosis

No other species of Chamalycaeus resembles Chamalycaeus mizoramensis sp. nov. The relatively large size, the fringed aperture, the dense, fine ribbing on R1 and R3, and the long R2+R3 (ca half whorl) are characteristic of this species.